Before I knew of The National Library of Manipulatives I created a smartboard program that taught my students how to subtract with regrouping. (Using unifix cubes.)
Overall, the kids enjoyed the lesson and were engaged throughout. After I showed them how to borrow and regroup, I had the students go to their seats to use whiteboards to practice subtracting, in a we-do format.
Since doing the lesson, I have been quite impressed with my students' subtraction with regrouping. They have been able to reference the unifix cube lesson and seem to apply what they learned weeks ago!
I'm thankful for the smartboard in many ways, however with this lesson I think I was most thankful. Last year, I did the same lesson with real unifix cubes. Instead of ungrouping them and moving them to a new column on the smart notebook page, I broke the cubes apart and put them into different pockets in a chart. PHEW. Last year it was a 'clunky' lesson that didn't flow, which inhibited the kids from truly learning the concept.
Yay for math.